There has been known a paint for automobiles which generally contains an acrylic polyol or polyester polyol, and a melamine resin as a curing agent. The paint is required to cure at a temperature of 130.degree. to 180.degree. C. for 10 to 30 minutes. The curing temperature is too high to apply to thermoplastic materials, such as synthetic plastics. It also requires a high energy cost.
A two-pack urethane paint containing an isocyanate as a crosslinking agent has also been used for repairing automobiles. The paint is short in pot-life and therefore inconvenient for actual application. Also, in this paint, the isocyanate having a low molecular weight remains in a cured film and causes toxicity.
It is desired that a coating composition can be cured at a low temperature, for example, 50.degree. to 150.degree. C. without using isocyanates to obtain a highly crosslinked film.